Electricity high voltage substations contain equipment such as current transformers, voltage transformers, breakers and so on. Anomalies within high voltage equipment's insulation can produce Electromagnetic Interference (EMI) within the substation.
The present invention seeks to analyse the EMI present in a substation to determine the location of potentially defective pieces of equipment and to output a transparent intensity map superimposed onto an aerial photo of a substation showing locations of faults.